1. Field of Invention
The present invention relates broadly to a power unit and more particularly to a novel power unit which can be readily used for medical and like stools, the length of which can be extended and retracted at will by the operator, and which comprises a ram, and cylinder in which the ram slides, an integral reservoir of oil pressurized by air, a valve or flow control, and at least one seal.
2. Prior Art
Ram power units for extending and retracting a ram within a cylinder have traditionally used oil or hydraulic reservoirs generally adapted only to the particular use to which the power unit is employed. Often the reservoir has been built into structures which actually form a part of an assembly including a ram power unit, so that use of the power unit in other applications has required additional adaptations and designs of the reservoir to be consistent with these other applications. While oil reservoirs have on occasion been built into the structure of the power unit itself, the reservoir has been made up of a multiplicity of component parts, including tubes, plugs, seals and fastening means, to make-up the reservoir. Further, such units have not been readily interchangeable or adapted to uses for other purposes.